1 /* 2 * arch/xtensa/kernel/time.c 3 * 4 * Timer and clock support. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2005 Tensilica Inc. 11 * 12 * Chris Zankel <chris@zankel.net> 13 */ 14 15 #include <linux/errno.h> 16 #include <linux/sched.h> 17 #include <linux/time.h> 18 #include <linux/clocksource.h> 19 #include <linux/clockchips.h> 20 #include <linux/interrupt.h> 21 #include <linux/module.h> 22 #include <linux/init.h> 23 #include <linux/irq.h> 24 #include <linux/profile.h> 25 #include <linux/delay.h> 26 #include <linux/irqdomain.h> 27 #include <linux/sched_clock.h> 28 29 #include <asm/timex.h> 30 #include <asm/platform.h> 31 32 unsigned long ccount_freq; /* ccount Hz */ 33 EXPORT_SYMBOL(ccount_freq); 34 35 static cycle_t ccount_read(struct clocksource *cs) 36 { 37 return (cycle_t)get_ccount(); 38 } 39 40 static u64 notrace ccount_sched_clock_read(void) 41 { 42 return get_ccount(); 43 } 44 45 static struct clocksource ccount_clocksource = { 46 .name = "ccount", 47 .rating = 200, 48 .read = ccount_read, 49 .mask = CLOCKSOURCE_MASK(32), 50 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 51 }; 52 53 static int ccount_timer_set_next_event(unsigned long delta, 54 struct clock_event_device *dev); 55 struct ccount_timer { 56 struct clock_event_device evt; 57 int irq_enabled; 58 char name[24]; 59 }; 60 static DEFINE_PER_CPU(struct ccount_timer, ccount_timer); 61 62 static int ccount_timer_set_next_event(unsigned long delta, 63 struct clock_event_device *dev) 64 { 65 unsigned long flags, next; 66 int ret = 0; 67 68 local_irq_save(flags); 69 next = get_ccount() + delta; 70 set_linux_timer(next); 71 if (next - get_ccount() > delta) 72 ret = -ETIME; 73 local_irq_restore(flags); 74 75 return ret; 76 } 77 78 /* 79 * There is no way to disable the timer interrupt at the device level, 80 * only at the intenable register itself. Since enable_irq/disable_irq 81 * calls are nested, we need to make sure that these calls are 82 * balanced. 83 */ 84 static int ccount_timer_shutdown(struct clock_event_device *evt) 85 { 86 struct ccount_timer *timer = 87 container_of(evt, struct ccount_timer, evt); 88 89 if (timer->irq_enabled) { 90 disable_irq(evt->irq); 91 timer->irq_enabled = 0; 92 } 93 return 0; 94 } 95 96 static int ccount_timer_set_oneshot(struct clock_event_device *evt) 97 { 98 struct ccount_timer *timer = 99 container_of(evt, struct ccount_timer, evt); 100 101 if (!timer->irq_enabled) { 102 enable_irq(evt->irq); 103 timer->irq_enabled = 1; 104 } 105 return 0; 106 } 107 108 static irqreturn_t timer_interrupt(int irq, void *dev_id); 109 static struct irqaction timer_irqaction = { 110 .handler = timer_interrupt, 111 .flags = IRQF_TIMER, 112 .name = "timer", 113 }; 114 115 void local_timer_setup(unsigned cpu) 116 { 117 struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); 118 struct clock_event_device *clockevent = &timer->evt; 119 120 timer->irq_enabled = 1; 121 clockevent->name = timer->name; 122 snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); 123 clockevent->features = CLOCK_EVT_FEAT_ONESHOT; 124 clockevent->rating = 300; 125 clockevent->set_next_event = ccount_timer_set_next_event; 126 clockevent->set_state_shutdown = ccount_timer_shutdown; 127 clockevent->set_state_oneshot = ccount_timer_set_oneshot; 128 clockevent->tick_resume = ccount_timer_set_oneshot; 129 clockevent->cpumask = cpumask_of(cpu); 130 clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); 131 if (WARN(!clockevent->irq, "error: can't map timer irq")) 132 return; 133 clockevents_config_and_register(clockevent, ccount_freq, 134 0xf, 0xffffffff); 135 } 136 137 void __init time_init(void) 138 { 139 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 140 printk("Calibrating CPU frequency "); 141 platform_calibrate_ccount(); 142 printk("%d.%02d MHz\n", (int)ccount_freq/1000000, 143 (int)(ccount_freq/10000)%100); 144 #else 145 ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; 146 #endif 147 clocksource_register_hz(&ccount_clocksource, ccount_freq); 148 local_timer_setup(0); 149 setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction); 150 sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); 151 clocksource_of_init(); 152 } 153 154 /* 155 * The timer interrupt is called HZ times per second. 156 */ 157 158 irqreturn_t timer_interrupt(int irq, void *dev_id) 159 { 160 struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; 161 162 set_linux_timer(get_linux_timer()); 163 evt->event_handler(evt); 164 165 /* Allow platform to do something useful (Wdog). */ 166 platform_heartbeat(); 167 168 return IRQ_HANDLED; 169 } 170 171 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 172 void calibrate_delay(void) 173 { 174 loops_per_jiffy = ccount_freq / HZ; 175 printk("Calibrating delay loop (skipped)... " 176 "%lu.%02lu BogoMIPS preset\n", 177 loops_per_jiffy/(1000000/HZ), 178 (loops_per_jiffy/(10000/HZ)) % 100); 179 } 180 #endif 181